A coordinate measuring apparatus of the kind described above has already been known for a relatively long time from the prior art.
For example, U.S. Pat. No. 3,639,993 presents a coordinate measuring apparatus of this type, which is frequently referred to as a bridge-type measuring device. The patent presents a coordinate measuring apparatus in which two horizontal longitudinal members are provided with horizontal guides which are parallel to each other and are each mounted via three vertical supports directly on the factory building floor located therebelow. A bridge slide is guided movably along the horizontal guides in a first coordinate direction. A cross slide is guided movably on the bridge slide in a second horizontal coordinate direction, the cross slide, in turn, movably guiding a spindle sleeve in the third coordinate direction, that is, in the vertical direction. A sensor via which the workpiece can be detected is fastened to the lower end of the spindle sleeve. In order to mount the workpiece, a workpiece table is provided between the guides which are oriented parallel to one another, the workpiece table being mounted on the factory building floor independently of the guides.
Coordinate measuring apparatuses of this type are often used in manufacturing environments and are particularly suitable for receiving large workpieces. The workpieces can be transported in a simple manner onto the front side of the workpiece table, for example with a crane or with a forklift truck. However, the workpiece table is also readily accessible laterally because of the raised guides and the vertical supports lying relatively far apart.
However, it is then problematic if the floor is deformed. Such a deformation can take place, for example, due to sinking of the substructure or due to heavy workpieces. This results in the mechanism of the coordinate measuring apparatus being deformed and considerable measurement errors occurring by this means.
Another coordinate measuring apparatus with a similar construction is known from U.S. Pat. No. 6,161,298. The patent presents a coordinate measuring apparatus in which two horizontal longitudinal members are likewise provided with horizontal guides which are parallel to each other and are each mounted via two vertical supports on a rectangular frame, wherein the frame, in turn, is mounted on the floor via vibration dampers. Each of the supports is mounted at the lower end tiltably on the frame and at the upper end is screwed to one of the longitudinal supports and, in addition, is stiffly connected in one or more directions via a connector to a concrete polymer body. The concrete polymer body here surrounds both the rectangular frame and the supports. So that the supports remain movable in relation to the concrete polymer body, tubes in which the supports run are cast in the concrete polymer body. A bridge slide is guided movably along the horizontal guides in a first coordinate direction. A cross slide is guided movably on the bridge slide in a second horizontal coordinate direction, the cross slide, in turn, movably guiding a spindle sleeve in the third coordinate direction, that is, in the vertical direction. A sensor via which the workpiece can be detected is fastened to the lower end of the spindle sleeve. For the mounting of the workpiece, a measuring table is mounted on the rectangular frame.
European publication 1335180 A2 discloses a coordinate measuring apparatus which is clearly very similarly constructed to the coordinate measuring apparatus according to U.S. Pat. No. 6,161,298. It is not described in detail therein how the vertical supports, on which the longitudinal members with the guides are fastened, precisely rest on the rectangular frame and how the supports are specifically cast in the concrete polymer and fastened thereto, since this is not the actual subject matter of the patent application. However, from the obvious correspondence of FIG. 4 of this document with FIG. 1 of U.S. Pat. No. 6,161,298, it is apparent that the same type of coordinate measuring apparatus is clearly involved here. Unlike in U.S. Pat. No. 6,161,298, in European publication 1335180 A2 the measuring table is not mounted on the rectangular frame. On the contrary, both the rectangular frame and the measuring table are mounted on four jointly used supporting elements. Warping of the coordinate measuring apparatus as a consequence of a high workpiece weight can thereby be avoided.
The coordinate measuring apparatuses presented in U.S. Pat. No. 6,161,298 and European publication 1335180 A2 have proven successful in the past. However, they are suitable only for relatively small workpieces. An enlargement of the coordinate measuring apparatuses to greater measuring volumes, with which even large workpieces can then be measured, is not readily possible. One of the reasons is that the concrete polymer body to be used would then be very large and also heavy and is therefore difficult to transport. In addition, when the coordinate measuring apparatus is enlarged, the problem would also arise that, in the event of a deformation of the floor, the loadings in the vibration dampers or supporting elements could change, causing the mechanism of the coordinate measuring apparatus to be deformed and considerable measurement errors to occur as a result.